MNT: raise exception if generators passed in

tacaswell · tacaswell · commit bdaaf594a647 · 2015-12-29T15:33:54.000-05:00
- moved next(iter(obj)) logic into a cbook function
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -2331,11 +2331,11 @@ def broken_barh(self, xranges, yrange, **kwargs):
         """
         # process the unit information
         if len(xranges):
-            xdata = next(iter(xranges))
+            xdata = cbook.safe_first_element(xranges)
         else:
             xdata = None
         if len(yrange):
-            ydata = next(iter(yrange))
+            ydata = cbook.safe_first_element(yrange)
         else:
             ydata = None
         self._process_unit_info(xdata=xdata,
@@ -5886,7 +5886,8 @@ def _normalize_input(inp, ename='input'):
                 Name to use in ValueError if `inp` can not be normalized
 
             """
-            if isinstance(x, np.ndarray) or not iterable(next(iter(inp))):
+            if (isinstance(x, np.ndarray) or
+                    not iterable(cbook.safe_first_element(inp))):
                 # TODO: support masked arrays;
                 inp = np.asarray(inp)
                 if inp.ndim == 2:
diff --git a/lib/matplotlib/cbook.py b/lib/matplotlib/cbook.py
@@ -12,6 +12,7 @@
 from matplotlib.externals import six
 from matplotlib.externals.six.moves import xrange, zip
 from itertools import repeat
+import collections
 
 import datetime
 import errno
@@ -2536,6 +2537,13 @@ def index_of(y):
         return np.arange(y.shape[0], dtype=float), y
 
 
+def safe_first_element(obj):
+    if isinstance(obj, collections.Iterator):
+        raise RuntimeError("matplotlib does not support generators "
+                           "as input")
+    return next(iter(obj))
+
+
 def get_label(y, default_name):
     try:
         return y.name
diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
@@ -1561,7 +1561,7 @@ def default_units(x, axis):
             x = x.ravel()
 
         try:
-            x = next(iter(x))
+            x = cbook.safe_first_element(x)
         except (TypeError, StopIteration):
             pass
 
